BQ77905: BQ77905 UV level is different from the data sheet

Hello Harry,

The UV threshold should be 2.0-V as specified in the datasheet. Do you see this with all your units? Could you share a picture of your IC and schematic so we can review them?

Best Regards,

Luis Hernandez Salomon

I attach our schematic and the picture of the IC.

110-0890-98-01 Rev B(VENDOR)_20230131.pdf

Hello Harry,

I checked the lot number for this part and it seems that it should be working okay and the UV threshold should be 2.0-V.

Do you see this issue in all of your parts? Can you also share your test procedure?

Best Regards,

Luis Hernandez Salomon

I use 450R resistors in serial to simulate the cell voltage.   After apply the voltage to IC and check the IC is in normal no-fault state.   Slowly decrease the voltage until the IC enters the fault state.   Record the trip voltage.  

There are 4 IC on each board.  We has tested three boards, the #1 UV 2.55V/recover 3.05,  #2 2.52/3.01 , #3 2.55/3.27V,   All three board has very good OV level at 3.9V.  

You can the UV level and recovery level are not very consistent as well. 

Hello Harry, 

Did you measure the voltage directly at the IC pins when they performed this test? 

This is odd. Do all of the faulty parts have the same markings? Have you found any ICs that have the correct value?

Best Regards,

Luis Hernandez Salomon

Hi Luis,

I place one IC into the BQ77905EVA.   The UV is correct at 2.0V.   I also configure the BQ77905EVA to 4 cell and did the similar configuration as mine design.  The UV is 2.0v as well.  

I can not understand as well.  

Could you look at my design and see anything that might cause the issue.  I don't not use current sense, LD,  so all this pin are shorted to ground.